Ocular Biometric Study During Accommodation

Abstract

Abstract-We performed this study to measure the ocular changes during accommodation and see whether refractive error has any influence in effect of changes during accommodation. This study was carried out in the Department of Ophthalmology, Pt. B. D. Sharma PGIMS, Rohtak. Seventy five subjects were divided in three groups according to refractive status. Group A consisted of 25 emmetropes. Group B consisted of 25 myopes with myopia <5 D while Group C consisted of 25 hypermetropes with hypermetropia <5 D. The subject was asked to focus on 6/6 line of Snellen's chart kept at a distance of 6 meters with full refractive correction with the left eye and A-scan was performed on the right eye. Three readings of anterior chamber depth, lens thickness and axial length were taken and the mean values of these reading were calculated. Similar procedure was repeated after accommodation. Accommodation was achieved by asking the subject to focus on N/6 line of near vision chart held at a distance of 33 cm with left eye with full refractive correction on the left eye. Then, the subjects were asked to focus N/6 line of near vision chart held at 12.5 cm to increase the amplitude of accommodation and similar procedure was repeated. The mean increase in axial length was 0.051, 0.004, and 0.005 mm in Groups A, B and C respectively when focus of the left eye was shifted from 6 m to 33 cm. On further increasing the accommodation by shifting the focus of the left eye to 12.5 cm, the axial length increased by 0.08, 0.07, and 0.007 mm in Groups A, B, and C respectively. Increase in lens thickness and decrease in anterior chamber depth were also observed with accommodation in all three groups. There was no significant difference in between three groups in these changes. Conclusions: Subtle but statistically significant increase in axial length was observed with accommodation in this study. There was increase in lens thickness and decrease in anterior chamber depth with accommodation. There was no variation with refractive error in these changes.

Whole Eye Axial Biometry During Accommodation Using Ultra-long Scan Depth Optical Coherence Tomography

“…With A-scan ultrasonography, no change in AL was observed during accommodation 2–4 whereas other studies reported an increase. 5, 6 Using partial coherence tomography, including the IOLMaster (Carl Zeiss Meditec, Dublin, CA) and Lenstar (Haag-Streit AG, Koeniz, Switzerland), AL has been found to increase during accommodation. 10, 14, 15 With advances in whole eye imaging using ultra-long scan depth optical coherence tomography (UL-OCT), 16–21 each compartmental dimension of the whole eye can be measured.…”